Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnly, idempotent, and closed-world. The description adds value beyond them by stating 'Costs nothing and makes no request' and describing the return content (five verdicts, meanings, next moves), which tells the agent this is a free static lookup with no side effects or latency. It does not elaborate on caching or exact output format, keeping it short of a 5.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two tight sentences with zero filler; the core purpose is front-loaded and the cost/latency note follows immediately. Every clause earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a zero-parameter, no-output-schema explainer, the description gives everything an agent needs: what it returns, when to call it, and that it is free and side-effect-free. No return schema exists, but the description adequately characterizes the output ('five verdicts, what each means, next move').

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The tool takes zero parameters, so the baseline is 4 per the rubric. No parameter semantics are needed, and the description does not need to compensate for any schema gaps.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb ('Return') and resource ('the five verdicts this index can return'), and distinguishes itself from siblings by being the explainer for access_check_url results. An agent can immediately tell this is a static reference tool, not another access check.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly says when to use it ('call it once to interpret access_check_url results') and frames the audience ('an agent that has just been refused'). It effectively names the related sibling access_check_url but does not state when not to use it or any exclusion; still, the guidance is clear enough for correct invocation.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.